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DC Injection Suppression in Transformer-less Grid Connected Inverter using a DC Link Current Sensing and Active Control Approach

Lookup NU author(s): Weichi ZhangORCiD, Dr Matthew Armstrong, Dr Mohammed Elgendy

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Abstract

IEEE There is increasing interest in the use of transformer-less systems for grid connected inverter photovoltaic applications. Compared to transformer coupled solutions, transformer-less systems offer a typical efficiency increase of 1-2%, reduced system size and weight, and a reduction in cost. However, the removal of the transformer has technical implications. In addition to the loss of galvanic isolation, DC current injection into the grid is a potential risk. Whilst desirable, complete mitigation of dc current injection via convention current control methods is known to be particularly challenging. For this reason, this paper proposes an active dc suppression method, in which the dc current injection is accurately determined by extracting the line frequency component from inverter dc link current measurements and then mitigated with an active closed loop controller. Experimental results from a laboratory grid connected inverter system are presented to demonstrate the high performance of the proposed technique.

Publication metadata

Author(s): Zhang W, Armstrong M, Elgendy MA

Publication type: Article

Publication status: Published

Journal: IEEE Transactions on Energy Conversion

Year: 2019

Volume: 34

Issue: 1

Pages: 396-404

Print publication date: 01/03/2019

Online publication date: 04/10/2018

Acceptance date: 02/04/2018

Date deposited: 06/02/2019

ISSN (print): 0885-8969

ISSN (electronic): 1558-0059

Publisher: IEEE

URL: https://doi.org/10.1109/TEC.2018.2874158

DOI: 10.1109/TEC.2018.2874158

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